diff options
Diffstat (limited to 'fs/pnode.c')
-rw-r--r-- | fs/pnode.c | 61 |
1 files changed, 49 insertions, 12 deletions
@@ -322,6 +322,21 @@ out: return ret; } +static struct mount *find_topper(struct mount *mnt) +{ + /* If there is exactly one mount covering mnt completely return it. */ + struct mount *child; + + if (!list_is_singular(&mnt->mnt_mounts)) + return NULL; + + child = list_first_entry(&mnt->mnt_mounts, struct mount, mnt_child); + if (child->mnt_mountpoint != mnt->mnt.mnt_root) + return NULL; + + return child; +} + /* * return true if the refcount is greater than count */ @@ -342,9 +357,8 @@ static inline int do_refcount_check(struct mount *mnt, int count) */ int propagate_mount_busy(struct mount *mnt, int refcnt) { - struct mount *m, *child; + struct mount *m, *child, *topper; struct mount *parent = mnt->mnt_parent; - int ret = 0; if (mnt == parent) return do_refcount_check(mnt, refcnt); @@ -359,12 +373,24 @@ int propagate_mount_busy(struct mount *mnt, int refcnt) for (m = propagation_next(parent, parent); m; m = propagation_next(m, parent)) { - child = __lookup_mnt_last(&m->mnt, mnt->mnt_mountpoint); - if (child && list_empty(&child->mnt_mounts) && - (ret = do_refcount_check(child, 1))) - break; + int count = 1; + child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint); + if (!child) + continue; + + /* Is there exactly one mount on the child that covers + * it completely whose reference should be ignored? + */ + topper = find_topper(child); + if (topper) + count += 1; + else if (!list_empty(&child->mnt_mounts)) + continue; + + if (do_refcount_check(child, count)) + return 1; } - return ret; + return 0; } /* @@ -381,7 +407,7 @@ void propagate_mount_unlock(struct mount *mnt) for (m = propagation_next(parent, parent); m; m = propagation_next(m, parent)) { - child = __lookup_mnt_last(&m->mnt, mnt->mnt_mountpoint); + child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint); if (child) child->mnt.mnt_flags &= ~MNT_LOCKED; } @@ -399,9 +425,11 @@ static void mark_umount_candidates(struct mount *mnt) for (m = propagation_next(parent, parent); m; m = propagation_next(m, parent)) { - struct mount *child = __lookup_mnt_last(&m->mnt, + struct mount *child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint); - if (child && (!IS_MNT_LOCKED(child) || IS_MNT_MARKED(m))) { + if (!child || (child->mnt.mnt_flags & MNT_UMOUNT)) + continue; + if (!IS_MNT_LOCKED(child) || IS_MNT_MARKED(m)) { SET_MNT_MARK(child); } } @@ -420,8 +448,8 @@ static void __propagate_umount(struct mount *mnt) for (m = propagation_next(parent, parent); m; m = propagation_next(m, parent)) { - - struct mount *child = __lookup_mnt_last(&m->mnt, + struct mount *topper; + struct mount *child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint); /* * umount the child only if the child has no children @@ -430,6 +458,15 @@ static void __propagate_umount(struct mount *mnt) if (!child || !IS_MNT_MARKED(child)) continue; CLEAR_MNT_MARK(child); + + /* If there is exactly one mount covering all of child + * replace child with that mount. + */ + topper = find_topper(child); + if (topper) + mnt_change_mountpoint(child->mnt_parent, child->mnt_mp, + topper); + if (list_empty(&child->mnt_mounts)) { list_del_init(&child->mnt_child); child->mnt.mnt_flags |= MNT_UMOUNT; |